Vehicle lifting mechanism



Oct. 30, 1962 .1. J. PELoUcH 3,050,900

VEHICLE LIFTING MEGHANISM Filed Nov. 9, 1960 5 Sheelzs-Sheei'I 1INVENTOR. JAMES J. PELGUCH BY fm1;

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'ATTORNEYS Oct. 30, 1962 Filed Nov. 9, 1960 J. J. PELOUCH lvial-HOLELIFTING MECHANISM 5 Sheets-Sheet 2 ATTORNEYS Oct. 30, 1962 J. J. PELoUcHVEHICLE LIFTING MECHANISM 5 Sheets-Sheet 3 Filed Nov. 9. 1960 .H Dof,...Tu No ma MP lm s E M A J l 4 4 ,wz

ATTORNEYS Oct 30, 1962 .1.J. PELoucl-l VEHICLE LIFTING MECHANISM FiledNOV. 9. 1960 INVENTOR.

JAMES PELOUCH Oct. 30, 1962 J. J. PELoUcH VEHICLE LIFTING MECHANISM 5Sheets-Sheet 5 Filed Nov. 9, 1960 INVENTOR.

JAMES J. PELOUCH r 'g t (n, 1 ii The invention relates in general tolifting devices and more particularly to vehicle lifts.

An object of the invention is to provide a lift having a piston andcylinder arrangement with valve means for controlling gas pressurebetween the piston and hydraulic liquid which is contained in thecylinder and in the specific embodiment also in the piston whichincludes a hollow construction.

Another object of the invention is to provide a lift which includes acylinder with a piston therein which is movable between upper and lowerpositions by the action of gas pressure acting between the piston andhydraulic liquid in the piston, with valve means for allowing andpreventing gas pressure buildup depending on the hydraulic liquid level.

Another object of the invention is to provide a vehicle lift with asafety valve for controlling the operation of the cylinder and pistondepending on the liquid level of the lift,

Another object of the invention is to provide a vehicle lift with asafety control valve which may be removed from the lift if necessarywithout the necessity of having to completely remove the lift pistonfrom the cylinder which is a comparatively large job.

Another object of the invention is to provide a vehicle lift with meansfor preventing dangerous operation which means, instead of preventingflow of hydraulic liquid between a hollow piston and a cylinder when theliquid level is too low, prevents the build up of gas pressure betweenthe piston and the hydraulic liquid.

Another object of the invention is to provide a vehicle lift having avertical cylinder with a hollow piston movable between upper and lowerpositions therein and hydraulic liquid in the piston and cylinder andtransferrable therebetween Vby passageway means in the lower portion ofthe piston, with valve means controlled by the hydraulic liquid levelwhereby if the liquid level is too low the valve prevents gas pressurebuildup and subsequent raising of the piston. Provision is also madewhereby the valve is positively kept closed when the piston is raisedthus insuring gas pressure buildup when desired in the raised conditionof the piston.

Another object of the invention is to provide a control apparatus forcontrolling the ow of a fluid from an enclosure which ow is caused bythe action of a gas under pressure.

Another object of the invention is to provide a control apparatus for afull hydraulic lift which prevents operation with insufcient hydraulicuid and permits operation with sufficient hydraulic huid and alsoinsures operation of the lift after the same has been raised.

Another object of the invention is to provide a lifting mechanism with acontrol which insures that the mechanisrn will not operate atdangerously low hydraulic fluid levels.

Another object of the invention is to provide a valve for a conduitwhich is controlled by a normal liquid level before operation and afteroperation a means is provided whereby the valve is maintained closedregardless of the liquid level.

Another object of the invention is to provide a full hydraulic liftwhich includes a hydraulic reservoir or tank and which is actuated withgas under pressure with a valve for the tank which prevents gasactuation if the 3,06%,960 Patented Oct. 30, 1962 hydraulic level is toolow and which permits gas actuation if the hydraulic level is proper andwith the valve having means which keeps the valve in a predeterminedposition so that after actuation it remains in such position regardlessof the hydraulic level.

Other objects and a fuller understanding of this invention may be had byreferring to the following description and claims, taken in conjunctionwith the accompanying drawings, in which:

FIGURE l is a side elevational View in section of the lifting mechanismof the present invention in its lower position;

FIGURE 2 is a side elevational view similar to FIGURE l but showing thelifting mechanism in raised position;

FIGURE 3 is a fragmentary side elevational view in section of the upperportion of the lift piston corresponding to that shown in FIGURE 1 butshowing the hydraulic oil or liquid at a proper level;

`FIGURE 4 is a plan view of the upper end of the piston shown in FIGURE3;

FIGURE 5 is a side elevational view showing a full hydraulic liftincorporating the teachings of the present invention;

FIGURE 6 is an enlarged fragmentary side elevational view of a portionof the apparatus shown in FIGURE 5;

FIGURE 7 is a view similar to FIGURE 6 but showing the valve in openposition; and

FIGURE 8 is a view similar to FIGURE 5 but showing the lift in the upposition.

The lifting mechanism of the present invention is peculiarly adapted foruse as -a vehicle lift and the forthcoming description taken along withthe drawings has been directed to this type of device. The vehicle liftillustrated is for the purpose of raising a vehicle from the door orground level which has been indicated generally by the reference numeral10. The lift includes a cylinder 12 positioned in substantially avertical position bel-ow ground level. A piston i3 is positioned withinthe cylinder and is Iadapted for movement between upper and lowerpositions in the cylinder. FIGURE 1 shows the piston in its lowermostposition in the cylinder and FIGURE 2 shows the piston in its uppermostor raised position within the cylinder. It will be noted from FIGURES land 2 that the piston comprises a hollow construction which includes acylindrical body 15 which is closed at its lower end by an end wall 16and at its upper end by first and second end plates 17 and 18,lrespectively, which are welded in position. An air or gas supply tubeor pipe 20 extends from the exterior of the lift axially into the hollowpiston construction, through the lower or first end portions or thepiston and cylinder to the upper or the second end portion of the pistonwhen it is in its lower position (FIGURE l). The end wall 16 of thepiston 13 is provided with an opening or passageway means 23 which isfor the purpose of providing fluid communication between the hollowpiston construction and the cylinder. An angle iron 24 is suitablysecured in position adjacent the passageway means Z3 and is for thepurpose of smoothing out liquid flow therethrough. An oil or hydraulicliquid conduit 27 is provided and communicates with the cylinder 12 forproviding the desired amount of hydraulic liquid or liuid to the hollowpiston and cylinder arrangement. The upper end of the conduit 27 iscovered by means of a threaded cap 2S and a dip stick 29 is located inthe upper end of the conduit 27 so that an operator may determine theliquid level at any time desired. The air tube 2@ extends to a suitableair supply such as a compressor and interposed in the tube is a suitablevalving arrangement which has not been shown which may be operated byhand or by other means for either supplying air under pressure to thepiston and cylinder arrangement or exhausting pressurized air therefrom.

A superstructure 31 is secured to the upper end of the piston 13 bymeans of a plurality of bolts 32 extending therethrough `and into theend plate 18. The superstructure carries the mechanism for engaging avehicle to raise the same from lloor or ground level a suicient verticaldistance upwardly to enable one to gain access to the underside of thevehicle. Secured to the superstructure by suitable means is a safety leg34 which travels with the superstructure and piston and is guided inthis travel by means of an annular guide member 35 which is suitablyrecessed in the floor or ground adjacent the cylinder 12. The safety legis provided with a notch or recess 37 (FIGURE 2) intermediate its upperand lower ends and into this recess a pivoted latch 38 is adapted toreside. 'I'he purpose of this construction is to insure that once thelift has been raised to its upper position that it will not accidentallybe lowered thereby damaging persons and property.

Wall means 40 (FIGURES 3 and 4) are provided in the upper end of thehollow piston construction 13 and more specically -in the end plates 17and 18 and an air Valve assembly 42 is mounted at this opening. The airvalve assembly 42 includes a closure member 45 secured in the opening 40by means of screws 46 extending into the end plate 17. `Passageway means48 are provided through the closure member for providing communicationbetween the hollow piston construction and the exterior of the liftmechanism or -in other words to the atmosphere. The closure member 45 isprovided with a valve seat 50. A valve 52 is adapted to move betweenopen and closed positions with the valve seat 50 to either allow orprevent iluid passage through the passageway means 48. 'I'he valve iscontrolled by means of a iloat member 54 and is connected thereto bymeans of a rod 55. TheV float resides within a guide tube 56 which isiixedly secured to the end plate 17 which closes the upper end of thehollow piston construction. The upper end of the guide tube 56 isprovided with openings 58 which provide for the passage of fluid to thepassageway means 48. The valve 52 is guided and supported by means of abracket which includes an apertured plate 60 secured to the closuremember by means of rods 61. A stop in the form of a cotter pin 63 isprovided in the end of the guide tube 56 to limit the travel of thefloat 54. The rod 55 is provided with a ilange or shoulder 65 `and avalve control weight 67 is pivotally connected to the guide tube '6between irst and second end portions thereof 68 and 69, respectively.The rst end portion 68 of the valve control weight 67 engages the airsupply tube 20 in the lower position of the piston and this keeps thesecond end portion 69 from engaging the ilange 65 on the rod 55. In theraised position of the piston the second end portion of the valvecontrol weight 67 engages the flange 65 because of its unsymmetricalmounting (FIGURE 2) and this insures that the valve 52 remains on theseat 50 when the piston is in a raised condition.

The passageway means 48 is provided with a flapper valve 71 which is forthe purpose of insuring that foreign matter does not enter thepassageway means 48, however the passage of gas from the interior of thepiston is not obstructed by the flapper valve. A first guide bushing 73is xedly secured in the interi-or of the hollow piston construction bymeans of a bar which is welded at opposed ends to opposite walls of thepiston. This bar is of a narrow width and does not obstruct lluid llow.A second guide bushing 74 is secured within the hollow pistonconstruction and is connected to the guide tube 56 of the air valveassembly. These two bushings 73 and 74 are for the purpose ofmaintaining the position of the air supply tube with respect to thepiston during raising and lowering movements of the piston.

Packing I88 is provided between the cylinder 12 and piston 13 to preventthe escape of hydraulic liquid on movement of the piston. A plurality ofstops 79 are positioned circumferentially around the walls of thecylinder 12 and are held in position by bolts 80. The stops are adaptedto be engaged by a plurality of lugs 81 circumferentially spaced aroundthe lower end Vof the piston 13 to limit upward movement of the piston.In originally assembling the piston 13 and cylinder 12 it is necessaryto tur-n the piston so the lugs 81 are out of alignment with the stops79 and then the piston can be put into position. The piston is thenagain turned to align the lugs and stops and the safety leg is attached.

As mentioned in the objects, one of the primary advantages of the liftof the present invention is that if the oil or hydraulic liquid is at anunsafe level, the lift will not function at all rather than functioningunder a dangerous condition. The dangerous condition results when theoil drops to such a level that if the piston were raised, the oil levelwould be below the end wall 16 of the piston. This would result in airacting upon the end wall 16 tending to urge the piston upwardly and airbeing compressible could build up an extremely high pressure and if thepiston stuck in the cylinder for some reason and then if loosened wouldurge the piston upwardly at eX- cess speeds resulting in possibledamage. Under normal operation with the air under pressure beingcontained within the hollow piston construction, the speed at which thepiston is permitted to travel upwardly and downwardly within thecylinder is determined -by the metering of hydraulic liquid through thepassageway or opening 23. FIGURE 3 illustrates the relative positions ofthe piston and the air intake tube when the piston is in the lowerposition. 'Ihis ligure also shows the hydraulic liquid or oil at aproper level in the piston and cylinder arrangement. It will be notedthat in this position the float 54 maintains the valve 52 in closedposition. FIGURE l illustrates the hydraulic oil or liquid level asbeing dangerously low and in this condition it will be noted that theiloat member 54 maintains the valve 52 in open position. The properliquid level shown in FIGURE 3 has been indicated by the referencenumeral 76 and the dangerously low liquid level of FIGURE l has beenindicated by the reference numeral 77.

In operation, assume that the hydraulic liquid level is proper (FIGURE3) and it is desired to raise the superstructure 31 from the ground oriloor level. To accomplish this end, air is introduced into the upperend of the hollow piston construction and this air under pressure exertsa force between the liquid level 76 and the end place 17 of the piston.With the valve 52 closed this pressure causes the piston to moveupwardly to the position shown in FIGURE 2. As the piston movesupwardly, the rst end 68 of the valve control weight `67 disengages theair supply tube 20 and the second end p0rtion of the control weightengages -the flange on the connecting rod 55. This insures that thevalve 52 is prevented from opening when it is desired to lower the liftand air pressure is removed from the hollow piston by way of the airsupply tube 20. It will be appreciated -that this is necessary since ifthe valve were not maintained in the closed position it would beimpossible to again pressurize the interior of the piston without havingcompletely lowered the superstructure. An example of this would be ifthe operator had neglected to release the latch y38 which cooperateswith the recess 37 on the safety leg and the superstructure has beenlowered to this position. It would be necessary to raise the piston andthe superstructure again in order to disengage the latch. With thisaccomplished the pressure could be removed from the piston 13. Theliquid level 78 shown in FIGURE 2 is in effect the liquid level 76 butlthis level is lower upon raising of the piston because of thedisplacement of the lower portion of the piston in the hydraulic liquid.

Let it be assumed now that the hydraulic liquid level is dangerously lowas indicated in FIGURE l and an attendant or operator is desirous ofraising the superstructure. With the oil at the level 77, the floatmember 54 causes the valve 52 to be opened or unseated, because there isnot enough oil to Ibuoy up the float member 54 and gravity causes thevalve to assume the position shown in FIGURE l. Upon the introduction ofair under pressure into the upper end of the hollow piston constructionthe `air immediately passes through passageway 4S past the ilapper valve71 and out to the atmosphere thereby preventing any pressure buildup.Without pressure buildup the lift cannot be raised at all and this alongwith the escape of air will readily bring it to the attention of anoperator of the device. In order to enable the mechanism to operate, itis necessary that he remove the cap 28 from the hydraulic liquid supplyconduit 27 and fill the piston cylinder arrangement with hydraulicliquid to a proper level as indicated by the dip stick 29. It will alsobe noted that when the piston is lowered to its lowermost position, thevalve control weight 67 is rendered inoperative and the only thingcontrolling the valve 52 upon an operator being desirous of raising thelift is the iloat which is in turn dependent upon the liquid level inthe hollow piston construction.

It will be noted that the present application discloses a lift whichincludes a cylinder and piston which piston is movable between upper andlower positions by gas pressure action between the piston and hydraulicliquid in the piston with valve means for allowing and preventing gaspressure buildup depending on the hydraulic liquid level. The presentinvention also provides a construction in a semi-hydraulic lift forrendering the lift ineffective when the lift is in a dangerouscondition. This stems from a control of the gas pressure which controlis in turn geared to the hydraulic liquid level. The valve mechanism bywhich this is accomplished may be easily removed from the lift ifnecessary without the necessity of having to completely remove the liftpiston from the cylinder. This is a comparatively expensive, and timeconsuming job. In the present construction all that is necessary ifsomething should go wrong with the valve is to remove the assembly bymeans of the screws 46. Another advantage of the present invention isthat when the hydraulic liquid drops to a dangerous level it simply willnot function and when the liquid level is proper the valve remainslclosed at all times. This is a great advantage over some of the presentday control mechanisms whereby when the liquid level reached a dangerouscondition the valve will open and close for a period of time with agreat deal of force and in many instances results in damage to the valveand valve seat. This problem is eliminated by use of the presentmechanism.

FIGURES 5 8 incorporate the teachings of the Present invention; however,the teachings have been incorporated into what is commonly referred toas a full hydraulic lift. The vehicle lifting apparatus shown inyFIGURES 5-8 has been indicated generally by the reference numeral 81yand includes in combination a cylinder 32 located below floor level S5land in a generally vertical position. A piston 83 is positioned in thecylinder and is adapted to be raised and lowered between the positionsshown in FIGURES 5 and 8. FIGURE 5 shows the piston in the fully loweredposition and FIGURE 8 shows the piston in the fully raised position.Packing 84 is positioned in a recess in the upper portion of thecylinder 32 and acts between the cylinder walls and the piston toprevent loss of hydraulic lluid from therebetween. The piston is raisedand lowered by the action of hydraulic uid which will be described inmore detail hereinafter.

It will be noted that the top of the cylinder is substantially even withthe floor level 8S in this construction in the down or lowered position.A vehicle engaging superstructure 88 is appropriately secured to theupper portion of the piston and is adapted to be raised and lowered inaccordance with the movement of the piston. The superstructure 88 isadapted to engage the under portion of vehicles to raise the same in amanner which is well known to those skilled in the art. A safety leg 89is secured to the superstructure 8S and is housed in a safety leghousing 90. The safety leg is for the purpose of providing a mechanicalconnection which insures that the lift cannot be lowered accidentally.The safety leg 89 also includes pin or obstruction means 91 which havebeen indicated only diagrammatically, the operation and purpose of whichwill be obvious from viewing FIG- URES 5 and 8.

A hydraulic fluid supply tank 94 is provided which has upper and lowerportions 95 4and 96, respectively. This supply tank has been shown aspositioned above the floor level 85; however, it will be appreciatedthat the supply tank may be located in many diiferent places. Ahydraulic iluid conduit 99 leads from the lower portion of the supplytank 94 to the cylinder S2. A valve 14H) is interposed in the conduit 99and permits ilow of hydraulic uid from the supply tank to the cylinderand prohibits ow of the same in the reverse direction unless the valve100 is actuated by an operator of the apparatus. An air supply tube 103extends from `a pressurized source of gas, not shown, such as air andextends through a hand operated valve 104 and into the upper portion ofthe supply tank 94. The valve 104 is such that it may provide flowtherethrough to the tank or it may prevent ow therethrough and exhaustthe tank to atmosphere. It will be noted in FIGURES 6 and 7 that adeector plate 195 is provided inside the supply tank and this is for thepurpose of preventing pressurized gas, such as air from blowing directlydown upon the surface of the hydraulic iluid which causes the hydraulicfluid to froth up or be entrained with air.

Wall means 106 define an opening in the upper portion of the supply tankand an air valve assembly indicated generally by the reference numeral107 is located in this opening. The air valve assembly includes aclosure member 1129 secured in the opening by way of threads 110 and isprovided with a valve seat 111. Passageway means 113 extend through theclosure member 109 and provide for communication between the interior ofthe upper portion of the supply tank and the outside atmosphere. Asupport member 116 is secured by a screw 117 to the closure member 109and extends generally vertically downwardly therefrom into the upperportion of the supply tank. A valve 119 is provided and is adapted toengage and disengage the valve seat 111 to open and close the passagewaymeans 113. A rod 120 is flxedly secured at one end portion to the valve119 and extends downwardly through spaced bearing members 121 :and 122which are carried by support member 116. A oat member 124 is providedwhich has a cylindrical opening 125 extending therethrough and the oatmember is located between the bearing members 121 and 122 with anintermediate portion of the rod member extending through the cylindricalopening 125. It will be noted that there is clearance between the rodand the cylindrical opening which enables the tloat member and rod tomove vertically relative to each other. Abutment means 127 are providedon the rod above the float member 124- and the abutment means in thisembodiment takes the form of a spring-like wire member wrapped tightlyaround the rod 120. Wall means 13) are provided on a lower portion ofthe support member 116 and deiine an inclined surface below the floatmember in line with the iloating vertical travel of the float member.

The operation of the lift mechanism shown in FIG- URES 5-8 will bedescribed hereinafter. Assume the hydraulic fluid level is at a satelevel indicated by reference numeral 133 in FIGURES 5 and 6, and thelift is in the lowered position as shown. All that is necessary is toactuate the valve 104 and pressurized air is introduced into the upperportion of the supply tank through tube 163. Since the hydraulic lluidis at a safe level 133i, the iloat member 124 is in engagement with theabutment means 127 which holds the valve 119 on the valve seat 111(FIGURES and 6). The pressurized air then acts upon the surface of thehydraulic fluid forcing the same through the hydraulic iluid conduit 99into the cylinder 82 thereby raising the lift to the position shown inFIGURE 8. When the lift has been raised, the safety leg S9 is set asshown in FIGURE 8 and the lift is mechanically prevented from lowering.It will be noted in FIGURE 8 that as the hydraulic fluid is forced outof the supply tank, the iioat member travels vertically downwardly andengages the inclined surface 130 wedging against the rod 1293. This,along with the action of the air pressure against the underface of thevalve 119 keeps the valve in closed position. When it is desired tolower the lift, all that is necessary is to disengage the pin means 91of the safety leg, depress valve 100, and let the air out of the upperportion of supply tank by means of the valve 104.

If the operator has inadvertently neglected to disengage the safety legand the above procedure is gone through, it will be noted that the airwill be exhausted from the upper portion of the supply tank and therewill be no air acting on the valve 119, and under normal circumstancesthe valve would drop open. Since the oat member is engaged with theinclined surface, the wedging action between the Ifloat member and therod prevents the valve from opening. As a result, the valve 103 can bereopened and air can be reintroduced into the upper portion of thesupply tank to raise the lift again so the safety leg can be disengaged.

If it be assumed that the lift is in the down position as shown inFIGURE 5 and the hydraulic fluid level is at an unsafe level 136,indicated in FIGURE 7, then the oat is positioned downwardly of thatshown in FIGURE 5 and as a result, the rod and valve member are also inthe down position because there is no means to tend to hold the same up.As a result, when air under pressure is introduced through the tube 103,it immediately travels through the passageway means 113 and out toatmosphere. This serves as an automatic warning to an operator that thehydraulic -uid level is dangerously low in the supply tank.

It will therefore be seen that a lifting mechanism has been providedwith a control which insures that the mechanism will not operate atdangerously low hydraulic fluid levels. The teachings incorporated intothe structure of FIGURES 5 8 illustrate how the overall teachings of thebasic invention can be incorporated into a full hydraulic lift asdistinguished from the lift of FGURES 1 4. The teachings of theinvention might be said to relate to a control apparatus for controllingthe `flow of fluid from an enclosure which iiow is caused bythe actionof a gas under pressure. The -full hydraulic lift which incorporates theteachings of the present invention includes -a hydraulic reservoir ortank which is actuated with a gas under pressure and the tank has avalve which prevents gas actuation if the hydraulic level is too low andwhich permits gas actuation if the hydraulic level is proper, and thevalve is also provided with means which keeps it in a predeterminedposition so that after actuation, it remains in such position regardlessof the hydraulic level.

This application is a continuation-impart of my application, Serial No.790,009, filed January 29, 1959, for Vehicle Lifting Mechanism, nowabandoned.

Although this invention has been described in its preferred form with acertain degree of particularity, it is understood that the presentdisclosure of the preferred form has been made only by way of exampleand that numerous changes inthe details of construction and thecombination and arrangement of parts may be resorted to withoutdeparting from the spirit and the scope of the invention as hereinafterclaimed.

What is claimed is:

l. A vehicle lift for raising a vehicle from floor level including incombination a cylinder located below said oor level and in a verticalposition, a piston positioned in said cylinder and comprising a hollowconstruction, said piston being movable between upper and lowerpositions in said cylinder, said piston and cylinder each having firstand second end portions, an air supply tube extending axially into saidpiston through said first end portion of said piston and cylinder tosaid second end portion of said piston in its lower position, passagewaymeans in said piston providing for fluid communication between saidfirst end portion of said piston and said first end portion of saidcylinder, an oil conduit communicating with said cylinder for supplyingoil to said cylinder and to said piston through said passageway means, asuperstructure, means securing said superstructure to said second endportion of said piston, a safety leg secured to said superstructure forpreventing accidental lowering of said piston, wall means defining anopening in said second end portion of said piston, an air valve assemblymounted at said opening, said air Valve assembly including a closuremember secured in said opening and having a seat valve, passageway meansthrough saidV closure member providing Vfor fluid communication betweensaid hollow piston construction and atmosphere, a oat member, a valveadapted to engage said valve seat, a rod xedly secured at one endportion to said float member and at the other end portion to said valve,a guide tube within which said float member resides, a flange on saidrod, a valve control weight pivotally mounted on said guide tube andhaving first and second end portions, said first end portion engagingsaid air supply tube in the lower position of said piston and keepingsaid second end portion from engagement with said flange, and saidsecond end portion engaging said flange in the upper position of saidpiston to insure that said valve remains on said valve seat.

2, A vehicle lift for raising a vehicle from -tloor level including incombination a cylinder located below said floor level and in a verticalposition, a piston positioned in said cylinder and comprising a hollowconstruction, said piston being movable between upper and lowerpositions in said cylinder, said piston and cylinder each having firstand second end portions, -a gas supply tube extending into said pistonthrough said first end portion of said piston to said second end portionof said piston in its lower position, passageway means in said pistonproviding for fluid communication between said first end portion of saidpiston and said -rst end portion of said cylinder, a hydraulic liquidconduit communicating with said cylinder for supplying hydraulic liquidto said cylinder and to said piston through said passageway means, asafety leg secured to said lift for preventing accidental lowering ofsaid piston, an air valve assembly mounted in said second end portion ofsaid piston, said air valve assembly including a valve seat, passagewaymeans through said piston providing for communication between saidhollow piston construction and atmosphere, a float member, a valveadapted to engage said valve seat, a rod tixedly secured at one endportion to said float member and at the other end portion to said valve,a 4guide tube within which said float member resides, a flange means onsaid rod, a valve control weight having first and second end portions,said first end portion engaging inoperative means in the lower positionof said piston to keep said second end portion lfrom engagement withsaid flange, and said second end portion engaging said flange in theupper position of said piston to insure that said valve remains on saidvalve seat.

3. A vehicle lift for raising a vehicle from floor level including incombination a cylinder llocated below said oor level and in a verticalposition, a piston positioned in said cylinder and comprising a hollowconstruction, said piston being movable between upper and lowerpositions in said cylinder, said piston and cylinder each having firstland second end portions, a gas supply tube extending into said pistonthrough said first end portion of said piston to said second end portionof said piston in its lower position, passageway means in said pistonproviding for fluid communication between said rst end portion of saidpiston and said rst end portion of said cylinder, a hydraulic liquidconduit communicating with said cylinder for supplying hydraulic liquidto said cylinder and to said piston through said passageway means, anair valve assembly mounted in said second end portion of said piston,said -air valve assembly including a valve seat, passageway meansthrough said piston providing for fluid communication between saidhollow piston construction and atmosphere, a 4iioat member, a valveadapted to engage said valve seat, means connecting said iioat memberand valve, a safety means engaging said valve in the upper position ofsaid piston to insure that said valve remains on said valve seat andmeans for rendering said safety means inoperative in the lower positionof said piston.

4. A lift mechanism including in combination ya cylinder, a pistonmovable between upper and lower positions in said cylinder, oil in thelower portion of said cylinder at a predetermined level, said oil andsaid piston defining an yair chamber, means for introducing air underpressure into said air chamber and for releasing the same, passagewaymeans -in said piston providing communication between said air chamberand the atmosphere, valve means carried by said piston and movablebetween open and closed positions for allowing and prohibiting owthrough said passageway means, a float member connected to said valvemeans and in said lower piston position and with suiiicient oil levelmaintaining said valve means in closed position, introduction of `airunder pressure into said air chamber causing said piston to move to saidupper position with said air under pressure maintaining said valve meansin closed position, safety weight means engaging said valve means in theupper position of said piston to maintain said valve means in closedposition even in the absence of air under pressure, and means forengaging said safety weight means in the lower position of said pistonto render the same inoperative and the position of said valve meansthereby being dependent upon said float member and said oil.

5. A lift mechanism -including in combination a cylinder, a pistonmovable between upper and lower positions in said cylinder, hydraulicliquid in the lower portion of said cylinder at a predetermined level,said hydraulic liquid and said piston defining a gas chamber, means forintroducing gas under pressure into said gas chamber and for releasingthe same, passageway means in said piston providing communicationbetween said gas chamber and the atmosphere, valve means carried by saidpiston and movable between open and closed positions for allowing andprohibiting flow through said passageway means, a iioat member connectedto said valve means and in said lower piston position and withsuliicient hydraulic liquid level maintaining said valve means in closedposition, introduction of gas under pressure into said gas chambercausing said piston to move to said upper position with said gas underpressure maintaining said valve means in closed position, safety meansengaging said valve means in the upper position of said piston tomaintain said valve means in closed position even in the yabsence of gasunder pressure, and means for engaging said safety means in the lowerposition of said piston to render the Sme inoperative and the positionof said valve means thereby being dependent upon said float member andsaid hydraulic liquid.

6. A lift mechanism including in combination a cylinder, a piston insaid cylinder movable between upper and lower positions, said cylinderadapted to contain a hydraulic liquid with the liquid and said pistondefining a chamber, -means for supplying pressurized gas to saidchamber, passageway means providing for communication from said chamberto the exterior of said lift mechanism, valve means carried by saidpiston and cooperating with said passageway means for closing `andopening the same depending upon the hydraulic liquid level in the lowerposition of said piston, means for engaging said valve means in theupper position of said piston for insuring that said valve means remainclosed, and means for rendering said means for engaging said valve meansinoperative in the lower position of said piston.

7. A vehicle lift for raising a vehicle including in combination acylinder located in a substantially vertical position, a pistonpositioned in said cylinder :and comprising a generally hollowconstruction, said piston being movable between upper and lowerpositions in said cylinder, a gas supply tube extending into said pistonthrough one end portion thereof `and extending to the other end portionof said piston, passageway means in said piston providing for fluidconmiunicating between said one end portion of said piston and the lowerend portion of said cylinder, a hydraulic iiuid passage communicatingwith said cylinder for supplying hydraulic iluid to said cylinder and tosaid piston through said passageway means, conduit means providing forcommunication from the other end portion of said piston to the exteriorthereof, valve means carried by said piston and cooperating with saidconduit means for closing and opening the same depending upon thehydraulic fluid level in said piston while the same is in its lowerposition, means cooperating with said valve means in the upper positionof said piston for insuring that said valve means remain closedregardless of the hydraulic uid level, and means for rendering saidmeans which cooperate with said valve means inoperative in the lowerposition of said piston whereby the condition of said valve means -isdependent on the hydraulic fluid level.

8. Vehicle lifting apparatus including in combination a cylinder locatedbelow iloor level and in a generally vertical position, a pistonpositioned in said cylinder and adapted to be raised and lowered andhaving a vehicle engaging superstructure connected thereto to move inaccordance with the movement of said piston, a hydraulic fluid supplytank having upper and lower portions, a hydraulic iiuid conduit leadingfrom said lower portion of said supply tank to said cylinder, an airsupply tube extending to said upper portion of `said supply tank, wallmeans deiining an opening in said upper portion of said supply tank, anair valve assembly mounted at said opening, said air valve assemblyincluding a closure member secured in said opening and having a valveseat, passageway means through said closure member providing forcommunication between said upper portion of said supply tank andatmosphere, a float member having a cylindrical opening extendingtherethrough, a valve adapted t0 engage said valve seat, a rod iixedlysecured at one end portion to said valve and extending 'through saidcylindrical opening in said iioat member and the other end portionslidably residing in a bearing member, abutment means on said rod abovesaid float member, wall means delining an inclined surface below saidfloat member in line with the floating travel thereof, said iioat memberwith suliicient hydraulic fluid level in said supply tank in the downposition of said piston engaging said abutment means to close said valveand with insuliicient hydraulic fluid level permitting said rod andvalve to lower thus opening said passageway means, said float member inthe up position of said piston lowering to engage said inclined surfaceto wedge said rod against said cylindrical opening in said float memberto insure that said valve remains on said valve seat in the up positionof said piston.

9. Vehicle lifting apparatus including in combination a cylinder with apiston positioned therein and adapted to be raised and lowered andhaving a vehicle engaging superstructure connected thereto to rnove inaccordance to the movement of said piston, a iiuid supply tank havingupper and lower portions, a -iiuid conduit leading from said lowerportion of said supply tank to said cylinder, a gas supply tubeextending to said upper portion of said supply tank, wall means definingan opening vin said upper portion of said supply tank, a valve assemblymounted at said opening, said valve assembly including a closure membersecured in said opening and having a valve seat, passageway meansthrough said closure member providing V.for communication between saidupper portion of said supply tank and atmosphere, a float member havingan opening extending therethrough, a valve vadapted to engage said valveseat, a rod secured at one end portion to said Valve and extendingthrough said opening in said float member and the other end portionslidably residing in a bearing member, abutment means on said rod abovesaid oat member, wall means defining an inclined surface below said oatmember in line with the floating travel thereof, said liloat member withsuicient fluid level in said supply tank in the down position of saidpiston engaging said abutment means to close said valve and withinsuicient iluid level permitting said rod and valve to lower thusopening said passageway means, said oat mem-ber in the up position ofsaid piston lowering to engage said inclined surface to wedge said rodagainst said opening in said float member to insure that said valveremains on said valve seat in the up position of said piston. yl0.Vehicle lifting apparatus including in combination a cylinder and apiston positioned therein and adapted to be raised and lowered, a uidsupply tank, a fluid conduit leading from said supply tank to saidcylinder, a gas supply tube extending to said supply tank, wall meansdefining an opening in a portion of said supply tank, a valve assemblymounted at said opening, said valve assembly including a closure membersecured in said opening'and having a valve seat, passageways meansthrough said closure member providing for communication between saidsupply tank and atmosphere, a oat member having an opening therethrough,a valve adapted to engage said valve seat, a rod secured at one endportion to said valve and extending through said opening in -said floatmember, abutment means on said rod above said float member, Wall meansdefining wedging surface means below said oat member in line with thefloating travel thereof, said oat mem-ber with sufcient uid level insaidsupply tank in the down position of said piston engaging saidabutment means to close said valve and with insufficient fluid levelpermitting said rod and valve to lower thus opening said passagewaymeans, said float member in the up position of said piston lowering toengage said wedging surface means to Wedge Said rod against said openingin said float member to insure that said valve remains on said valveseat in the up position of said piston.

11. Vehicle lifting apparatus including in combination a cylinder and apiston positioned in said cylinder and adapted to be moved between rstand second position, a -uid supply tank, a uid conduit leading from saidsupply tank to said cylinder, a gas supply tube extending to said supplytank, wall means defining an opening in said supply tank, a gas Valveassembly mounted at said opening, said gas valve assembly including aclosure member secured in said opening and having a valve seat,passageway means through said closure member providing for communicationbetween said supply tank and atmosphere, a oat member having an openingextending therethrough, a valve adapted to engage said valve seat, a rodsecured at one end portion to said valve and extending through saidopening in said oat member `and the other end portion slidably residingin a bearing member, abutment means on said rod above said float member,and wall means defining an inclined surface below said oat member inline with the floating travel thereof.

12. A control apparatus for controlling the flow of a liquid from anenclosure formed by Wall means into which enclosure a gas under pressureis adapted to be introduced including in combination conduit meansproviding for communication from the enclosure to the exterior thereof,valve means carried by the Wall means which define the enclosure andcooperating with said conduit means for closing and opening the samedepending on the liquid level in the enclosure while the liquid is atits inoperativelevel in the enclosure, means cooperating with said valvemeans when gas under pressure is in the enclosure and the liquid levelis at its operative level for insuring that said Valve means remainclosed regardless of the liquid level, and means for rendering saidmeans which cooperate with said valve means inoperative while ltheliquid is at its inoperative level whereby the condition of said valvemeans is dependent on the liquid level.

13. A hydraulic lift including in combination wall means defining anenclosure for containing hydraulic uid, first conduit meanscommunicating with said enclosure for the passage of hydraulic uid toand from said enclosure, second conduit means communicating with saidenclosure for introducing gas under pressure into an upper portion ofsaid enclosure to force the hydraulic iluid out said first conduitmeans, passageway means in said Wall means which define said upperportion of said enclosure to provide for the exit of gas from saidenclosure, Valve means for opening and closing said passageway means tocontrol the air pressure in the upper portion of said enclosure, saidvalve means being controlled by the hydraulic lluid level in saidenclosure when there is substantially no gas pressure in the upperportion of said enclosure in the inoperative condition of said lift andin this situation said valve means being closed when the hydraulic uidlevel is at a determined safe level and being openV when the hydraulicfluid level is at a determined unsafe level, introduction of pressurizedgas into said upper portion of said enclosure `through said secondconduit means in the closed condition of said valve means causing atleast a portion of said hydraulic fluid to travel through said rstconduit means from said enclosure to lower the hydraulic fluid level inan opera- `tive condition of said lift and means exclusive of thepressurized gas in said upper portion of said enclosure cooperating withsaid valve means when the hydraulic fluid level is lowered in theoperative condition of said lift whereby said valve means remains closedregardless of the hydraulic uid level.

14. A liquid flow apparatus including in combination a tank having upperand lower portions, liquid conduit means for transmitting liquid to andfrom said lower portion of said tank to provide inoperative andoperative liquid levels, gas conduit means for pressurizing said upperportion of said tank to force liquid through said liquid conduit meansto provide the operative liquid level, and passageway means in saidupper portion of said tank providing communication therefrom toatmosphere, valve means `at said passageway means for opening andclosing same, said valve means at the inoperative liquid level beingopen or closed depending on the liquid level in the tank and meanscooperating with said valve means at the operative liquid level forinsuring that said valve means remains closed regardless of the liquidlevel in said tank.

References Cited in the le of this patent UNITED STATES PATENTS1,841,900 Lunati s Ian. 19, 1932 1,868,935 Breneman luly 26, 19322,336,817 Thompson Dec. 14, 1943 2,550,882 Sturm et al May 1, 19512,705,502 Thompson Apr. 5, 1955

